Then I coat the remote end while the injected core is still molten. The goal is to cover the entire end, covering both wires (which are flush with the plastic end). This keeps water from reaching the contacts. If you suspect that your rope lights will get some abuse on their ends, you could use the adhesive lined heat shrink tubing and pinch about 1/2" of the tubing together while its glue is molten (using a pliers) to make a stronger, sealed end.